ObjectiveTo investigate the expression regulation of inflammation cytokines interleukin 4 (IL-4), IL-6, IL-13, and tumor necrosis factor α (TNF-α) in rats with sciatic nerve defect following olfactory ensheathing cell (OEC) transplantation. MethodsThe primary OEC for cell culture and identification was dissociated from the olfactory bulb of the green fluorescent protein-Sprague Dawley (GFP-SD) rat. One hundred SD rats were randomly divided into 2 groups, and the right sciatic nerve defect (10 mm in length) model was made, then repaired with poly (lactic acid-co-glycolic acid) (PLGA). The mixture of equivalent cultured GFP-OEC and extracellular matrix (ECM) was injected into both ends of PLGA nerve conduit in the experimental group (n=55), and the mixture of DMEM and ECM in the control group (n=45). The general situation of rats was observed after operation. At 6 hours, 1 day, 3 days, 1 week, 2 weeks, 3 weeks, 4 weeks, and 6 weeks, the inflammatory cytokines were detected by Western blot. At 2, 4, and 6 weeks, the survival of GFP-OEC was observed in the experimental group. At 9 weeks, HE staining was used to observe the morphology of nerve tissue, and the sensory and motor function and the electrophysiological index were detected. ResultsThe cultured primary cells were GFP-OECs by immunofluorescence staining. Compared with the control group, the experimental group showed significantly increased expression level of IL-4 at 2-6 weeks (P < 0.05), significantly decreased expression level of IL-6 and TNF-α at 3 days and 1 week (P < 0.05) and significantly increased expression level of IL-13 at 1 day and 3-6 weeks (P < 0.05) by Western blot detection. At 2, 4, and 6 weeks, the surviving GFP-OEC of regenerative nerve end was observed in the experimental group under the fluorescence microscope. At 9 weeks, regenerative nerve tissue was loose, and cell morphology was irregular in the experimental group, while the regenerative nerve tissue had vesicular voids and the cell number decreased significantly in the control group. At 9 weeks, the functional recovery of sciatic nerve in the experimental group was better than that of the control group, showing significant difference in the lateral foot retraction time, sciatic nerve function index, muscle action potential latency, and the amplitude of compound muscle action potential (P < 0.05). ConclusionOEC can promote the anti-inflammation cytokines expression of IL-4 and IL-13 and inhibit the pro-inflammatory cytokines expression of IL-6 and TNF-α, which can improve the local inflammatory microenvironment of sciatic nerve and effectively promote the structure and function recovery of sciatic nerve.